This project will aim at the development of instruments, diagnostic criteria, and procedures necessary to conduct a planned, geographically based epidemiologic study of Alzheimer's Senile Dementia. With the help of staff from Health Research, Inc., methods to identify patients with senile dementia of the Alzheimer type (SDAT) will be developed. Examination of the criteria most critical in the diagnosis of SDAT patients will be made. The reliability and validity of the procedures developed will be determined.